I haven't told'em anything

They're just making that assumption because I always avoid conversations about relationships.
I normally work in room with another guy and girl. The girl is married and the guy is divorced, they each have kids. They're always talking about their relationships and I've always avoided getting involved in those conversations. A few months ago they were talking about their "first time" and then when they turned and asked me, instead of making up a story I just responded in a nasty tone "you dont know me well enough to be askin me that shit."
Thus began the "he's never had a girlfriend" and "he's a virgin" jokes

they get pretty brutal sometimes, but i've got pretty good at ignoring them